The invention relates generally to the field of network transmission media, and more particularly to network cables which include multiple conductors.
Conventional network cables that include multiple conductor pairs generally also include a crossweb which is designed to maintain a fixed separation between the multiple conductor pairs so as to reduce crosstalk. The crossweb is also commonly referred to as a xe2x80x9cflute.xe2x80x9d By way of example, in a conventional network cable of a type commonly known as a xe2x80x9cCategory 6xe2x80x9d cable, as described in ANSI/EIA/TIA-568.B2, which is hereby incorporated by reference herein, there are four twisted pairs and a crossweb which is arranged between the twisted pairs. The crossweb typically includes a central region at the center of the cable and fins extending from the central region to separate the twisted pairs from one another.
A significant problem that can arise when using a crossweb in a Category 6 cable or other type of network cable relates to the amount of material required to implement the crossweb. Crosstalk reduction may dictate that the crossweb fins have a designated thickness. However, increasing the thickness of the crossweb fins in order to improve the crosstalk performance of the cable is generally not desirable for many cable designs because the extra material may degrade burn performance, which can result in the cable not meeting designated fire safety performance standards. This is particularly problematic for cables that must meet fire safety ratings such as the well-known Communications Plenum Cable (CMP) or Nonhalogen International Electrotechnical Commission (IEC) 60332 Part 3C ratings. Increasing the thickness of the crossweb fins also increases the cost and size of the cable, while reducing its flexibility. Conventional cables with standard crossweb shapes fail to optimize material usage to achieve the best electrical, physical and fire safety performance.
A need therefore exists for an improved network cable which can provide a reduction in crosstalk without significantly increasing the amount of material used to implement the crossweb, thereby meeting fire safety, cost, size and flexibility requirements.
The invention provides a network cable having an improved crossweb structure which overcomes one or more of the above-specified drawbacks of conventional cables.
In accordance with one aspect of the invention, a network cable comprises a plurality of conductors, and a crossweb running longitudinally along at least a portion of a length of the conductors. The crossweb has a central region approximately in a center of the cable and a plurality of fins extending outwardly from the central region, with a given one of the fins separating at least a first one of the conductors from at least a second one of the conductors. At least the given one of the fins has a variable thickness along a cross-sectional length thereof from the central region to an opposing end of the fin with a maximum of the variable thickness being in a portion of the fin between the central region and the opposing end of the fin. For example, in an illustrative embodiment of the invention, each of the fins of the crossweb has a substantially elliptical shape along its cross-sectional length.
In accordance with another aspect of the invention, the maximum thickness of a given one of the fins may substantially correspond to a center of a corresponding one of the conductors, e.g., a center of a twisted pair conductor. The variable thickness along the cross-sectional length of the given one of the fins may increase from a portion of the fin adjacent the central region of the crossweb to a maximum thickness near a center of an associated one of the conductors, and decrease from the maximum thickness near the center of the associated one of the conductors to an end of the fin away from the central region. The variable thickness may be at a minimum thickness at the portion of the fin adjacent the central region of the crossweb.
Advantageously, the invention can provide a reduction in crosstalk in a network cable without requiring a corresponding increase in crossweb material, and thus without negatively impacting the fire safety, cost, size and flexibility requirements of the cable.